Analysis of interferon-gamma producing cells during infections by Yersinia enterocolitica O:9 and Brucella abortus in cattle.

One of the major constraints in the diagnosis of animal brucellosis is the cross-reactivity that occurs between Brucella and Yersinia surface antigens. With the aim to find a method to distinguish Brucella from Yersinia infection, the expansion of interferon gamma producing (IFN-γ+) T cell subsets obtained from peripheral blood mononuclear cells (PBMC) isolated from cattle either infected by Brucella abortus or experimentally immunized with Yersinia enterocolitica O:9 were compared. The lymphocytes were analyzed by flow cytometry after PBMC were in vitro re-exposed to Yersinia or Brucella antigens. The results highlighted a statistically significant difference in the expansion of the CD4+ and CD8+ IFN-γ+ T cells occurring when PBMC of animals immunized with Yersinia are in vitro exposed to Y. enterocolitica O:9 antigen but not to Brucella antigen. This method could thus be suggested in those cases where results obtained by serodiagnosis need to be further clarified.